gamma correction

Adjustments applied during the display of a digital
representation of colour on a screen in order to compensate
for the fact that the Cathode Ray Tubes used in computer
monitors (and televisions) produce a light intensity which
is not proportional to the input voltage. The light
intensity is actually proportional to the input voltage raised
to the inverse power of some constant, called gamma. Its
value varies from one display to another, but is usually
around 2.5.

Because it is more intuitive for the colour components (red,
green and blue) to be varied linearly in the computer, the
actual voltages sent to the monitor by the display hardware
must be adjusted in order to make the colour component
intensity on the screen proportional to the value stored in
the computer's display memory. This process is most easily
achieved by a dedicated module in the display hardware which
simply scales the outputs of the display memory before
sending them to the digital-to-analogue converters.